The present invention relates to a seat cushion frame for supporting the seat cushion in a vehicle seat assembly and in particular to a seat cushion frame made of a composite plastic insert molded with a metal reinforcing material.
The seat cushion frame of vehicle seat assemblies have typically been produced from a stamped steel sheet. A stamped steel cushion frame can be made relatively inexpensive however, a stamped steel cushion frame is relatively heavy. To reduce the weight of a seat cushion frame, it is possible to injection mold a cushion frame using a high strength engineered plastic resin such as Valox HS433 or Nydur BKV 130. Cushion frames can be made with such high strength engineered plastic resins with a weight savings of approximately 30% compared to the stamped steel cushion frame. However, the weight savings comes at a substantial cost penalty. The weight savings is not significant enough to justify the additional cost.
Lower cost and lower weight plastic resins such as polypropolene and polyethylene terephthalate can be used providing a substantial weight savings compared to both the stamped steel cushion frames and the high strength plastic resin cushion frames and also at a lower cost. However, the strength of a cushion frame made solely of these lower weight and lower cost resins is not adequate.
Accordingly, it is an object of the present invention to provide a seat cushion frame of low cost and low weight plastic resin that is reinforced to provide the necessary strength to the cushion frame.
It is an advantage of the present invention that the reinforced plastic seat cushion frame can be made with a substantial weight savings compared to a stamped steel frame at only a slight increase in cost.
It is a further advantage of the present invention that the reinforced plastic seat cushion frame can be made with a weight savings compared to a high strength plastic resin seat cushion frame and at significantly lower cost.
The seat cushion frame of the present invention is made by insert molding a metal reinforcing material with the low cost low weight plastic resin to reinforce the plastic resin to prevent brittle fracture during high loading. By insert molding either expanded metal or wire cloth in the areas of high stress in the cushion frame, the tendency of the plastic to fracture in a brittle manner is greatly reduced. The metal reinforcing material in the areas of high loading utilizes the ductility of the metal to prevent the sudden fracture of the plastic.
The reinforcement material can be placed throughout the seat cushion frame or can be limited to those regions of the cushion frame that experience high loading. The reinforcing material used can be either an expanded metal or a wire cloth both of which have a multiplicity of interstices that are filled with the plastic resin when the resin is molded around the reinforcing material.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.